系统主要对循环水泵、滤网以及其出口的蝶阀进行控制，其I/O点数为300多点，要求实现数据采集、程序控制等功能，同时电站控制室内保留少量的后备仪表和主要的操作开关，并将数据通过光缆传送至操作员站。能实现通过CRT对循环水系统进行控制。系统设有必要的手操开关，当控制系统出现故障时，不影响设备的手动运行。　　总体改造内容如下：　　(1) 根据循环水泵投运、启停及联锁要求将循环水泵控制室相关控制监视及操作信号送入改造后的循环水泵控制系统。　　(2) 保留原动力柜，系统只接受电源掉闸信号。　　(3) 所有泵、滤网等启停开关均设计在操作员站人机界面上，同时在电站集控室保留部分重要操作开关。　　(4) 在循环水系统控制室及现场水泵房安装摄像设备，以监视设备运行状况，并将视频信号送入工程师站和操作员站中。　　(5) 所有开关量与模拟量信号通过可编程控制器送入工程师站，并通过光缆及以太网将数据传输到操作员站。3 系统选型及特点　　为了满足上面提到的循环水控制系统的设计要求，我们选用罗克韦尔自动化产品A-B SLC 500可编程控制器（PLC）和研华公司IPC-610工控机（IPC）构成的自控系统，再配以先进的A-B RSView32组态软件来实现循环水控制系统的各项功能。　　可编程控制器（PLC）是专为工业环境下应用而设计的工业控制计算机，已经成为电气控制系统中应用为广泛的核心位置，它不仅能实现复杂的逻辑控制，还能完成各种顺序或定时的闭环控制功能，并且抗干扰能力强、可靠性高、稳定性好、体积小，能在恶劣环境下长时间、不间断运行，且编程简单，维护方便，并配有各类通讯接口与模块处理，可方便各级连接。 　　在当前先进的控制系统产品中，罗克韦尔的可编程控制器技术已相当成熟，而且从硬件的可靠性、稳定性及软件的易操作性等各方面综合评定，也符合循环水系统改造的各项要求。更为我们所需要的是SLC 500系列处理器内置了不同通讯接口，提供了多种控制器联网方式供用选择，可构成不同要求的工业监控网络，并且还提供了与各类“智能”设备的现场总线接口。终，使控制系统将参数检测、程序控制、显示报警、监控管理等融为一体，通过计算机处理、网络数据共享等技术手段，实现系统的集中管理，以满足系统运行现代化的要求，提高其性和效率性。4 系统网络结构　　循环水控制系统网络结构，如图2所示。5.系统功能　　循环水控制系统主要由数据采集及监视（DAS）和逻辑控制两部分组成。　　DAS主要完成数据一览、组显示、点显示、实时趋势、历史趋势、流程图、报警一览、报警历史、操作说明、报表打印等功能。各种功能均可通过主菜单单选择进入，并分级子菜单方式进行选用操作，大部分功能有热键调用，相关画面上下关联操作。　　控制系统主要通过上位机的软手操实现对阀门和泵的控制，并在程序中实现联锁功能。控制过程分为：

　　(1) 开循环水泵前，先打开蝶阀至30％，然后启泵，循泵开启之后再对蝶阀进行调节；关循环水泵时，先关蝶阀至30％，然后停泵，循泵停运后再将蝶阀完全关闭。

　　(2) 其它联锁保护功能。

　　(3) 有关设备的启停控制。6 结论　　本文讨论了基于可编程控制器的电站循环水控制系统的设计与实现，充分发挥了可编程控制器配置灵活、控制可靠、编程方便和可现场调试的优点，使整个系统的稳定性有了可靠保障。该控制系统已通过静态与动态联锁试验及试运过程，在实际应用中达到了改造设计要求，实现了预期目标，为电站的经济运行提供了保障。同时，我们认为在相关项目改造中值得推广及应用。主要介绍炼钢厂风机自动化控制系统等。关键词：

　　变频器  PLC  WinCC  PROFIBUS-DP 上位机1 系统简介the disc system. The cumulative flow Q = k * t * ∑ G, G is instantaneous flow, t is belt velocity, K is proportional coefficient. According to the instantaneous flow rate of each sampling time, the average flow rate of the previous period (10S) before sampling time is calculated, and compared with the given value of the flow rate of the upper computer, the deviation is obtained, and then the PID operation is carried out to obtain the control quantity, finally, the DC signal of 4 ~ 20MA is output by d/a template, which is used as the given value of DC drive control unit, and the speed of motor is changed to control the material flow. 3.2 Instrument Control (1) signal acquisition and processing using the special function of Concept software, according to different analog input signals and different parameters, the DFB of engineering quantity conversion, digital filter, deviation, upper and lower limit alarm and other signal processing are programmed respectively. These function blocks can be called directly in the control program. It has realized the level measurement and alarm of upper and lower limit of material level, the temperature measurement of mixture, the accumulation and instantaneous display of gas flow and oxygen flow, the measurement of gas and air pressure, the low pressure alarm and the cutting off of low pressure gas, negative pressure measurement and display, sinter layer thickness detection. It has realized the measurement of inlet flow rate, inlet exhaust gas negative pressure, temperature, motor bearing and stator temperature and over-temperature alarm. 2) ignition furnace temperature control ignition furnace combustion control is an important part of sintering process, there are two ways: proportional automatic control and single loop control. When the proportional automatic control is selected, the computer takes the temperature of the ignition furnace as the main regulating parameter and the gas flow and air flow as the auxiliary regulating parameter. The output of the temperature regulator is used as the set value of the gas flow regulator, and the output of the temperature regulator is used as the set value of the air regulator after the calculation of the air-fuel ratio, and then the PID regulation is carried out to realize the automatic control of the opening of the gas regulator and the air regulator. When single-loop control is selected, according to the set value of on-site input flow and the actual measurement value, single-loop PID calculation is carried out to control the gas and air flow control valve respectively, and to distribute its flow rate to control the temperature of ignition furnace. The single loop control chart is shown in figure 3. The system features (1) realize the integration of three electric power. The system on-site detection signal directly into the PLC, electrical control to remove the intermediate interlock. Operation Mode is divided into automatic and machine